Influence of temperature on size-dependent predation by a fish (Gasterosteus aculeatus) and a jellyfish (Aurelia aurita) on larval capelin (Mallotus villosus)

1997 ◽  
Vol 54 (12) ◽  
pp. 2759-2766 ◽  
Author(s):  
J K Elliott ◽  
W C Leggett

We compared the size-dependent mortality patterns of newly emerged larval capelin (Mallotus villosus) at three different temperatures (3, 9, and 15°C) when exposed to predation by threespine stickleback (Gasterosteus aculeatus) and moon jellyfish (Aurelia aurita). Controlled experiments were conducted in both microcosms (38 L) and mesocosms (3100 L). Some temperature-related trends were evident in experiments with sticklebacks, but not with jellyfish. Sticklebacks fed selectively on smaller capelin larvae at 15°C, were nonselective at 9°C, and fed on larger larvae at 3°C. There was no prey size selection by A. aurita at any of the temperatures examined. Our findings support the view that the direction and magnitude of size-selective predation vary depending on the predator-prey assemblage and environmental conditions examined.


2009 ◽  
Vol 66 (10) ◽  
pp. 1693-1706 ◽  
Author(s):  
Elvar H. Hallfredsson ◽  
Torstein Pedersen

Predation has been suggested as a cause of substantial mortality of fish larvae to the degree that it might influence recruitment. This field-based study concludes that juvenile herring ( Clupea harengus ) as small pelagic predator can significantly affect mortality rates of the planktonic larvae of capelin ( Mallotus villosus ) in the Barents Sea. Surveys were carried out in the summers of 2001 and 2003. In 2001, juvenile herring were widely distributed and overlapped with capelin larvae over a wide area, whereas in 2003, the herring were more aggregated. The study focused on predation in the areas of predator–prey overlap. Capelin larvae were observed in the herring stomachs at 11 of 24 stations and at 8 of 16 stations where herring were caught in 2001 and 2003, respectively. At those stations, an estimated 7.3% and 9.9% of the capelin larvae were eaten by herring per day in 2001 and 2003, respectively. Statistical models revealed that density of capelin larvae and copepods and occurrence of euphausiids in the stomachs affected the number of capelin larvae per predator stomach. A simplified model with only capelin larvae density as predictor was converted to a functional response relationship using an experimentally derived digestion rate estimate for capelin larvae in herring stomachs.



1983 ◽  
Vol 40 (9) ◽  
pp. 1442-1448 ◽  
Author(s):  
Kenneth T. Frank ◽  
William C. Leggett

We examined the biological basis of the synchrony between the onset of a pelagic existence in beach-spawned capelin (Mallotus villosus) larvae and the unpredictable occurrence of favorable predator–prey conditions caused by onshore winds. Larvae isolated from the in situ beach sediments, but subject to those changes in water mass characteristics as might remain when such water is introduced into an experimental constant-level tank, emerged in synchrony with larvae in situ. This supports the hypothesis that the larval response to wind-induced water-mass exchange is an active one; it represents an adaptation maximizing feeding success and minimizing mortality due to predation. This "opportunistic" life-stage transition has direct parallels in seed dormancy and diapause in insects.





1993 ◽  
Vol 50 (7) ◽  
pp. 1541-1547 ◽  
Author(s):  
Lenore Fahrig ◽  
George R. Lilly ◽  
Daniel S. Miller

We demonstrate a direct relationship between the amount of prey (capelin, Mallotus villosus) in its predators' stomachs (Atlantic cod, Gadus morhua) and the biomass of the prey in the same localities. The relationship at a local scale implies that predator stomach contents can be used to estimate prey distribution. There is no evidence for either (1) a negative effect of local predator abundance on stomach contents (expected if local prey depletion and/or feeding interference occurs when predator density is high) or (2) a negative effect of the amount of other food in cod stomachs on the amount of capelin in the stomachs (expected if prey switching occurs). There is a negative effect of bottom depth on amount of capelin in cod stomachs as expected, since capelin are pelagic and cod are primarily bottom-dwelling, resulting in less vertical overlap between the species in deep water. This type of analysis may be useful in other predator–prey systems. Simultaneous stomach samples and independent biomass estimates of the prey are required, but once the model is built, it permits estimation of prey distribution in places and times when no direct survey of the prey can be done.



Hydrobiologia ◽  
2020 ◽  
Author(s):  
Alexandra Loveridge ◽  
Cathy H. Lucas ◽  
Kylie A. Pitt

AbstractScyphozoan jellyfish blooms display high interannual variability in terms of timing of appearance and size of the bloom. To understand the causes of this variability, the conditions experienced by the polyps prior to the production of ephyrae in the spring were examined. Polyps reared from planula larvae of Aurelia aurita medusae collected from southern England (50°49′58.8; − 1°05′36.9) were incubated under orthogonal combinations of temperature (4, 7, 10 °C) and duration (2, 4, 6, 8 weeks), representing the range of winter conditions in that region, before experiencing an increase to 13 °C. Timing and success of strobilation were recorded. No significant production of ephyrae was observed in any of the 2- and 4-week incubations, or in any 10 °C incubation. Time to first ephyra release decreased with longer winter incubations, and more ephyrae were produced following longer and colder winter simulations. This experiment indicates that A. aurita requires a minimum period of cooler temperatures to strobilate, and contradicts claims that jellyfish populations will be more prevalent in warming oceans, specifically in the context of warmer winter conditions. Such investigations on population-specific ontogeny highlights the need to examine each life stage separately as well as in the context of its environment.



2021 ◽  
pp. 102614
Author(s):  
Florian Berg ◽  
Samina Shirajee ◽  
Arild Folkvord ◽  
Jane Aanestad Godiksen ◽  
Georg Skaret ◽  
...  


Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3013
Author(s):  
Leszek Czechowski

The paper deals with an examination of the behaviour of glued Ti-Al column under compression at elevated temperature. The tests of compressed columns with initial load were performed at different temperatures to obtain their characteristics and the load-carrying capacity. The deformations of columns during tests were registered by employing non-contact Digital Image Correlation Aramis® System. The numerical computations based on finite element method by using two different discrete models were carried out to validate the empirical results. To solve the problems, true stress-logarithmic strain curves of one-directional tensile tests dependent on temperature both for considered metals and glue were implemented to software. Numerical estimations based on Green–Lagrange equations for large deflections and strains were conducted. The paper reveals the influence of temperature on the behaviour of compressed C-profile Ti-Al columns. It was verified how the load-carrying capacity of glued bi-metal column decreases with an increase in the temperature increment. The achieved maximum loads at temperature 200 °C dropped by 2.5 times related to maximum loads at ambient temperature.



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